Safety control apparatus for rock drills



Oct. 3, 1933.

G. M. NELL SAFETY CONTROL APPARATUS FOR ROCK DRILLS Filed May 7, 1930 INVENTOR. g wfal e M A e// A TTORNE Y.

Patented Oct. 3, 1933 UNITED STATE-S.

SAFETY ooN'rnoL APPARATUS Iron noon DRILLS Gustave M. Nell, Detroit, Mich, assignor to Chicago Pneumatic Tool Company, New'York, N. Y., a corporation of New Jersey Application May 7, 1930. Serial No; 450,362

- 20 Claims- This inventionrelates to fluid pressure rock drilling machines otthe percussive type provided with power means for feeding the same to the work. Such drills with extensible feed legs are ordinarily referred teas stopers, More particularly the invention relates to improved apparatus for maintaining'control of the machine in emergencies andduring hole starting. V

As is well known considerable danger is. in-

volved in operating astoping drill, particularly when it is of the self-rotating type, due to the fact that when thedrill steel becomes stuck the machine as a'whole revolves winding up the hose which supplies motive fluid to the machine.

r When-this happens suddenly it may cause the operator tolose his balance and fall, or he may be struck by parts of the revolving machine before he can shut off the motive fluid. Another dangerous situation develops-when the drill steel breaks. The sudden expansion of the pneumatic feed leg causes the drilling machine to shoot forward and if the operator attempts to close the ordinary type of throttle valve he may be injured by the broken drill steel. If he succeeds in closing the throttle valve, the machine is liable to collapse and may fall upon him.

Among the objects of the invention are to give the operator completeicontrol of his machine at all times and especially. in critical situations such as indicated above; to place certain of the control mechanism within his' grasp while, guiding the machine so as to be instantly available; to arrange certain parts of the control mechanism to operate automatically; to prevent both sudden extension and sudden collapse of the feed motor, and in general to improve prior arrangements in the interest of safety as well as of efficiency. r r

The invention provides 'for the automatic throttling either partially or completely, of some or all of the motors of a rock-drilling machine when the operator releases his guiding grasp also be made for passing pressure fluid to the chuck parts of the machine subject to or-independently of the previously mentioned controls. All'of the above is additional to but preferably subordinated toa main throttle or control valve. In order to: illustrate the invention one concrete embodiment thereof is shown in the accompanying drawing in which:

Fig. 1 is a fragmentary view largely in section of so much of afluidpressure stoping machine as is ary to illustrate the invention, the controls han shown'in the operating position for both the percussive motor and the feed motor;

Fig. 2 is a detail sectional view showing the safety control for the percussive motor in closed position; I

Fig. 3 is a-detail sectional view of the mainthrottle valve substantially on the line 3--3 of Fig. 1;

Fig. 4- is a view similar to Fig. 3 but showing the valve in closed position; and

Fig. 5 is a detail sectional view of part of the safety-control shown in Fig. l, but on a larger scale' The emoodim'ent of the inventionchosen for the purpose of iliustration comprises a self-rotating stoper having a'percussive motor indicated generally at A, a 'feed motor indicatedgenerally at B, and an intermedlateportion C containing the controls. The parts may be maintained in assembled relation by suitable means such as clamping bolts having heads 3 at oneend and nuts 4 atthe other. Both motors may-be oi any suitable or desired type. The percussive motor, which is supplied with motive fluid through a passage a, comprises cylinder 5 within which reciprocates a'hanimerflpistono which is stepped around during'reciprocations by suitable rotation mechanism including a rifle bar 7 and rifle nut 8. A passage 9 leads down through the wall of cylinder 5* to direct pressure fluid carrying ontrained lubricant to the chuck parts (not shown)" and to prevent the cuttings fromfa-ll'ing back into the front endof the-machine, when the latter is used in uprightposition. The feeding motorIB takes the form of a conventional feed leg having an outer cylinder 10 and an extensible piston member 11 therein, the movement of which is effected by motive, fluid reaching the interior of the cylinder by a passage 1). Since the percussive motor andthe feed motor form no part of the present invention, further description thereoi is omitted; t

The admission of motive fluid to the stoping machine is controlled by a main throttle valve 12 of conventional form adjustably mounted in ajfitting 13 and. provided with a control handle 12a; The fitting has a restricted port 14 there throughand the valve has a restricted port 15 for a pusposepresently to be described.

The invention involves additional means for controlling varying the operation of one or both of motors A and B independently of and without changing the adjustment of throttle valve 12. Such means include a safety device for stopping percussive motor A in an emergency. In the preferred arrangement herein shown the guide handle 17 is'utilized for this purpose; It is secured to a threaded cap 18 which closes the large end of a transversebore in part C. A threaded locking collar 19 may be used to clamp guide handle 17 securely in place. Handle 17 is made hollow to serve as the inlet for motive fluid, a threaded nipple being provided at 20 to which fitting 13 of main throttle valve 12 is conveniently connected. A screen s may be disposed in handle 17 to prevent passage of foreign material in the motive fluid and lubricant may be supplied through plug p.

The safety device comprises a valve or head 21 mounted on a rod 22 slidably supported in bearings 23 and 24 in hollow handlel'l, the head 21 being normally forced by the pressure of the entering motive fluid and by a coil spring 25 to close bore 21a (Fig. 2) of intermediate member C so as to out 01f the admission of motive fluid through passage a to percussive motor A. The grip extension 17a of guide handle 17 is cut away to receive a manual control lever 26 which is pivoted at 2'7 and extends through a loop portion 22a of rod 22for the purpose. of retracting plunger valve 21. As indicated in Fig. 1,-the operator holds lever 26 in retracted position when he grasps handle extension 17a thus permitting percussive motor A to operate. But the instant he releases his grip the pressure. of the entering motive fluid and spring 25 force the plunger head 21 to closed position (Fig. 2) and stop the percussive motor. A plug 28 retains bearing 24 in place and serves as a stop for rod 22. r V

The safetydevice just described does not fully cut oif motive "fluid to feed motor B since it doesnot close a passage 29 which has a restricted port 30 communicating with passage 31 whence a port 32 leads to bore 33 from which extends passage b to the feed motor. Hence, even when safety valve 21 is closed, as indicated Fig. 2, motive fluid in restrictedamount determined by the size of port 30 continues to. pass to feed motor 3 so that the latter will not collapsebut rather will feed-forward or extend slowly.

. Passage 31 .is restricted slightly at 31a to form a port opening into bore 21a which port is controlled by a check valve in the form of a ball 34 maintained adjacent the port by a stop pin 35. This valve is important since it admits motive fluid in considerable volume from bore 21a when safety valve 21 is in retracted or open position (Fig. 1) to insure adequate power for feeding the stoper forward when percussive motor A isin operation, but immediately closes port 31a to prevent venting of the feed motor through the percussive motor when safety valve 21 is closed (Fig. 2). Accordingly, check valve 34 is essential to prevent sudden collapse of the feed motor when the safety valve 21 is closed to stop percussive motor A.

To give the operator complete control at all times of the feeding motor a normally inoperative control member is provided for effecting a gradual relief of the pressure in the feed leg. In the form shown a push member 36 is slidably supported in a guide member or plug 37 threaded into bore 33 in intermediate member C for moving valve head 38 into contact with a seat in port 32. A spring 39 normally maintains plung-' er 36 and valve 38 at the limit of their outward movement and port 32 unobstructed save for an extension 38a on the valve head which projects through port 32 and carries aneedle end 38b in line with restricted port 30. When plunger 36 is forced inwardly, head 38 closes port 32 but permits motive fluid to flow in lesser degree through a small angular passage 38c. At the same time valve head 38 permits partial escape of pressure in the feed leg to atmosphere by uncovering a vent passage 40 in guide member 37. The quantity of fluid escaping through vent passage 40 exceeds that supplied through restricted passage 380 with the result that pressure in the feed leg is'gradually weakened. Needle end 381) is smaller than port 30 and its sole purpose is to clean port 30 in the event that the same becomes clogged with foreign matter such as rust, dirt, chips, etc.

The operation of the stoping machine may be described as follows. Assuming that the operator is about to start the drilling of a hole he supports the machine with his hand on grip 17a but with safety control handle 26 in the closed position shown in Fig. 2. He then opens main throttle valve 12 sufllciently to close ports 14 and 15 but to allow a restricted flow of motive fluid into the stoping machine. The percussive motor is shut off since safety valve 21 is seated over bore 21a but passage 29 is open and motive fluid enters the feed motor through port 30, passage 31, port 32, bore 33 andpassage b, slowly feeding the drill upwardly until the drill steel strikes the face of the rock. Ball valve 34 will go to closed position to prevent the escape of motive fluid from is against its stop 35 thereby admitting motive fluid in considerable volume through large port 32 to augment the air previously admitted through restricted port 30 to the feed motor. Due to the small size of the port 30, the air previously admitted through this port does not have sufficient pressure to hold the check valve 34 on its'seat against the pressure of live air admitted through passage 39a.

.If the drill steel becomes stuck the operator releases safety lever 26 whereupon safety valve 21 closes automatically (Fig. 2), immediately stopping the percussive motor and the rotation of the drill steel so that there is no rotating of the machine as a whole. Also, the feed leg cannot collapse because check valve 34 promptly closes port 31a and motive fluid continues to be fed to the feed motor through restricted port 30, which'takes care of any possible leakage. Auxiliary control plunger 36 may be manipulated by the operator while he pushes and pulls upon guide handle 17 to release the steel. Having released the drill steel he again grips safety lever 26 and the drilling continues as before. When' the operator is ready to bring the machine to collapsed position to change the drill steel, safety In view ofthe function of the passage 29 in admitting air to the-feed motor, it might appear at first that the passage 31a is unnecessary. However, if the passage 29 is designed to perform the functions described above, it will not have suflicient capacity to obviate the necessity of passage 31a and check valvef34. The passage 29 may be of areaequal-to that of passage 31 a but its entrance to the feed motor is very materially restricted at the port 30. If passage 29 did not have the restriction 30 the feed would jump more or'less violently when the valve 12 is opened. The relatively small capacity of port 30 is insuflicient in itself, because there is almost always a certain'amount of leakage presentjparticularly past the feed cup leathers, which is considerable when the latter have been in use for any appreciable time. Furthermore, face joints become battered and leaky after use, largely as a result of muck entering when disassembled and again assembled and being forced hard on the faces. Even assuming all faces are of perfect shape and there is no leakage whatsoever, when the hammer motor is operated by the opening of valve 21, the hammer piston reciprocations may cause a violent relative reciprocation of the feed piston in the feed cylinder, and the feed therefore does not have its full power because the compression reciprocation forces air out of the feed faster than it can reenter back through the small port 30 and the mean effective pressure in the feed is thereby lowered. Furthermorein the usual application of this type of machine, gravity has considerable effect on the rearward impulse and tive pressure in' the feed is higherthan it would countered in operating a self-rotating stoper and isrof especial value in starting or collaring a holein which case there is a tendency for the machine as a whole to crawl and get away from the operator. It is also of importance, in cases of a broken or stuck steel, in that danger is avoid-' ed due to the fact that the operator has practically inst'antaneous means of shutting off hishamf mer motor without liability of the feed motor collapsing suddenly. Many other advantages will be apparent to the experienced operator.

While the invention has been herein disclosed to closed position'when manually released, and

means for preventing sudden fluctuations of mo- Therefore, in practice, the check 3 tive fluid pressure insaid feed motor when said valve'cuts off the motive fluid supply to said percussive motor.

2. In a fluid pressure operated stoping drill, a percussive motor, a feed motor therefor, a motive fluid control member having means operating automatically to shut off the motive fluid to said percussive motor, a fluid passageway for the feed motor and means controlling the admission of motive fluid to and the venting of the same fror'nsaid feed motor, the last-mentioned means being so constructed and arranged to maintain the feed motor againstsudden collapse and sudden extension when said membercuts off the motive fluid supply to said percussive motor, and including'a valve for automatically blocking the fluid passageway to the feed motor."

3. In a drilling machine having a percussive motor and a feeding motor, control means for said motors including a valve having means automatically actuating the same'to' shut off the motive fluid supply to said percussive motor, means providing for the admission and egress of pressure fluid to and from said feeding motor including a relatively small portan'd a relatively larger port, and means effective when said valve goes to closed position for preventing egress of pressure fluid from said feeding motor through said larger port. a a

a 4. A stoping machine having a percussivemotor ,and a feeding motor, means for supplying motive fluid to said motors including'a passage having a small port and 'a second passage having a' relatively larger port for passing pressure fluid toQand from said feeding motor, a spring-pressed valve arranged to be held manually in retracted position and when released automatically-shutting offv the supply of motive fluid to said larger 7 port, and means preventing egress of pressure fluid from saidfeeding motor through said larger port to said percussive motor while permitting fluid to flow to and from said feeding motor i and mutually independent controls for said motors, andmeans yieldingly maintaining-one of said additional controls in closed positionto provide a safety cut-off for one of said motors.

6. In a drilling machine having a percussive motor and a feeding motor, a single control for fluid for both said motors, additional subordinate and mutually independent controls for-said motors, means yieldingly maintaining one of'said additional controls in closed position to provide a safety'cut-off for one of said motors, and means yieldingly maintaining the control for the other motor in open position.

7. In a'drilling machine having a percussive motor and a feeding motor, a main throttle valve for controlling the admission of motive fluid to the machine, a spring pressed plungerfor cutting off the supply ofmotive fluid to one of said motors, a guide handle on said machine, and manual means on said handle for moving said plunger from closed position to admit motive fluid.

8. In a drilling machine having a percussive motor and a feeding motor, a main throttle valve having a grip portion, and means including an actuating lever on'said grip portion for moving said plunger to open position. Y

. 9. A fluid pressure stoping machine having a percussive motor, a feed leg for, advancing said motor, a main throttle valve for controlling the admission of motive fluid to the machine,a resiliently actuated-safety cut-01f valve normally in closed position to close off the percussive motor from the fluid supply, said stoper having a restrictedport uncontrolled by said cut-elf valve for passing motive fluid to said feed leg, 9. larger supply port for motive fluid for said feed leg under control of said cut-oil valve, and valve means for controlling both said ports. 10. A fluid pressure stoping machine having a percussive motor, -a feed leg for advancing said 'motor, a self-closing valve normally in closed position for cutting off the supply of motive fluid to said percussive motor, a normally open passage uncontrolled by said valve having a restricted port for passing motive fluid in limited amount to said feed leg, an additional passage under control of said valve having a port for supplying motlve fluid in larger quantity to said feed leg, and means for preventing reversemovement of fluid in said additionalpassage; V

11. A fluid pressure stoping machine having a percussive motor, a feed leg for advancing said motor, a self-closing valve normallyfin closed position for cutting off the supply of motive fluid to said percussive motor, a normally openpassage uncontrolled by said valve having a'restricted port for passing motive fluid in limited amount to said feed leg,.an' additional passage under control of said valve havlng a portfor supplying motive fluid in larger quantity to said feed leg, and a manually operable valve member for controlling one of said ports.

12. A fluid pressure stoping machinehaving a percussive motor, a feed leg for advancing said motor, a valve normally in'closed position for cutting ofl the supply of motive fluid to said percussive motor, a normally open passage uncontrolled by said valve having a restricted port for passing motive fluid in limited amount to said feed leg, an additional passage under control of said valve having a port for supplying motive fluid in larger quantity to saidfeed leg, said ports being in alignment, and a normally open manually operable valve for controlling one of said ports and for cleaning the other.- j

13. A fluid pressure stoping machine having a percussive motor, a feed leg for advancing said motor, a valve normally in closed position for cutting off the supply of motive fluid to said percussive motor a normally open passage uncontrolled by said valve having a restricted port for passing motive fluid in limited amount to said feed leg, an additional passage under control of said valve having a port for supplying motive 14. A fluid pressure stoping machine having a manually operable valve member for controlling said larger port, said stoper'having a normally closed vent controlled by said member.

14. ,A fluid pressure stopping machine having a percussive motor, a feed leg for advancing said motor, a valve normally in closed position for cutting off the supply of motive fluid to said percussive motor, a normally open passage uncontrolled by said valve having a restricted'port for passing motive fluid in limited amount to said feed leg, an additional passage under'control of said valve having a port for supplying motive fluid in larger quantity to said feed leg, means for preventing reverse movement of fluid in said additional passage, and manually operable means arranged to control one of said ports and to provide a vent for said feed leg.

15. A percussive drilling machine having a fluid pressure feed motor for advancing the machine to the work and a'plurality of supply passages for motive fluid, said passages having differential ports in alignment, and a normally open spring actuated valve plunger having a head to close the larger of said ports and an extension projecting through said larger port to clean said smaller port.

16. A percussive drilling machine having a fluid-pressure feed motor for advancing the ma chine to the work and a plurality of supply passages for motive fluid, said passage having differential ports in alignment, and a'normally open spring actuated valve plunger having a head to close the larger of said ports and an extension projecting through said larger port to cleansaid smaller port, said machine having a venting passage uncovered by said head whensaid plunger is moved to close said port, and means on said head permitting fluid in limited amount to pass the same when said plunger is moved to portclosing position.

17. A percussive drilling machine having a fluid pressure feed motor for advancing the machineto the work and a passage for supplying motive fluid to said feed motor, a manually controlled valve plunger having a head for controlling said passage, said machine having a venting passage uncovered by said head when said plunger is moved to close said port, and means on said head permitting fluid in limited amount to pass thesame when said plunger is moved 1 to port-closing position.

1.8. In a drilling machine having a percussive motor and a feeding motor, a single control for the motive fluid to said machine, additional sub ordinateand mutually independent controls for said motors, means yieldingly maintaining the independent control for said percussive motor in closed position to provide a safety cut-off', and means preventing sudden release of motive fluid fromsaid feeding motor.

19. In a drilling machine having a percussive. motor and a feeding motor, a single control for the motive fluid to said machine,- additional subordinate and mutually independent controls for said motors, a fluid connection between said motors, means yieldingly urging the independent control for said precussive motor to closed position to provide a safety cut-oil, and. means pre venting venting of said feeding motor through said connection and said percussive motor when said safety cut-off operates to stop said percussive motor. I

20., In a drilling machine having a percussive motor and a feeding motor, a single control for the motive fluid to said machine, additional subordinate and mutually independent controls for said-motors, a fluid connection between said motors, means yieidingly urging the independent control for said percussive motor to closed position to provide a safety cut-off, and a check valve in said fluid connection for preventing venting of said feeding motor through said connection and said percussive motor when said safety cut-off operates to stop said percussive motor. I

GUSTAVE M. NFLL.

SERTIFIQATE (PF eomaeo'rioez.

Patent No. 1,928,730. @eioizer 3, 1933.

GUSTAVE re. NELL.

it is hereby certified that error appears in the printed speeiiieetieiioi the above numbered eateet requiring correction follows: Page 4, 62., eiaim l3, strike out the numeral and Words '14. A fluid pressure sioping maeiiine having" and insert instead fluid in larger quantity to said iced leg, and; and line 66, claim 14, for "stopping" read stoning; am! that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of November. A. D. 1933.

F. M. Hopkins (Seal) Acting Commissioner of Patents. 

